The present invention relates to a process for the preparation of hydrogen cyanide from acetonitrile. In particular, it relates to a process for preparing hydrogen cyanide from crude acetonitrile produced during the manufacture of an unsaturated nitrile such as acrylonitrile.
As is well known, hydrogen cyanide is an important substance which is frequently employed as a starting material for various organic reactions, and its consumption is expected to increase more and more.
Industrially, hydrogen cyanide has been mainly produced by ammoxidation of methane and is also obtained as a co-product in the preparation of acrylonitrile by the catalytic ammoxidation of propylene in the well known Sohio Acrylonitrile Process developed by the assignees of the instant application.
U.S. Pat. No. 3,516,789 discloses a process for the manufacture of hydrogen cyanide by reacting acetonitrile over an ammoxidation catalyst. The preferred procedure of this patent is the reaction of the acetonitrile produced during the manufacture of acrylonitrile by recycling the acetonitrile through the ammoxidation reactor over the ammoxidation catalyst. Moreover, U.S. Pat. No. 3,911,089 discloses the preparation of hydrogen cyanide by the addition of methanol to the ammoxidation reactor using the production of acrylonitrile to further increase the yield the hydrogen cyanide. Both of these patents have disadvantages which are overcome by the process of the present invention.